This application claims the priority of German patent document 100 26 245.7, filed 26 May 2000 (PCT International Application PCT/EP01/05434, filed 12 May 2001), the disclosure of which is expressly incorporated by reference herein.
This application is related to co-pending U.S. patent application Ser. No. 10/296,343, filed Jul. 24, 2003.
The invention relates to a method and a network for exchanging data between a plurality of subscribers via a data bus.
Modern vehicles frequently include several (preferably standardized) data buses. For engine and chassis components, for example, one system is used which is adapted to that application, while another suitably designed bus system is used for audio and telecommunication peripheries. Data exchange between the different bus systems takes place by way of a plurality of gateways.
An attempt to transfer this bus system architecture which is used in higher-priced vehicles to vehicles of the lower cost, however, results in high expenditures, due on the one hand, to the high costs of the standard bus for engine and chassis components and, on the other hand, to the cost of a gateway. The construction of a separate onboard network structure for lower priced vehicles is problematic in that it is largely impossible to take over individual components of the higher-priced vehicles because of a lack of compatibility. In addition, a conflict arises due to differing goals. To lower the cost, the transmission rate can be reduced and the number of bus subscribers can be increased, which results in long response times and low flexibility, because subscriber numbers differ from one vehicle to the next. Every addition of a new subscriber (for example, as a result of a subsequently installed component) requires considerable adaptation expenditures.
It is an object of the invention to provide a highly efficient method of exchanging data between several subscribers via a data bus which can serve a plurality of subscribers that vary in a vehicle-specific manner.
The onboard network structure according to the invention is modular and cost-effective. It permits the use of the same basic components in all vehicles covering several model series of a manufacturer. The higher-quality vehicles can be arbitrarily equipped with additional components, without being more expensive than comparable series systems.
A prerequisite for the invention is the existence of a faster data bus, such as for example the data bus described in German Patent Documents DE 19636441 A and DE 19636442 A. This data bus is distinguished by a transmission rate of more than 5 Mbits/s and is suitable, for example, for passive safety systems, such as air bags, belt tighteners, and the like, as well as the pertaining sensor system and actuators and their control units.
The control units are situated at different points of the vehicle (for example, in the area of the transmission tunnel or the B-columns, in the door or at the steering column). All such control units are connected with the data bus which, in normal situations (that is, outside a crash phase or serious misuse phase), is not utilized to a great degree. The same applies to the utilization of the processors in the control units.
According to the invention, these control units are also used for other functions. These functions are part of a different function periphery, for example, the electronic system of the vehicle body, and relate, for example, to the light control, the wiper control, the central locking system and the window lift mechanism control.
The light control and the wiper control, on the one hand, and the central locking system and the window lift mechanism control, on the other hand, are each a component of a subordinate data bus. Because of the minimized number of subscribers (in the case of the light control, for example, one control unit and 10 connected subscribers), the subordinate data bus has a sufficient response time and is also operable at a low transmission rate. That is, it rapidly and securely provides the connected subscribers with the required data, or it to be provided. As a result it is possible to connect control units in the electronic system of the vehicle body (with higher demands on the communication) directly to the faster data bus.
With such an onboard network structure, the need for a separate data bus for the components of the electronic system of the vehicle body is eliminated, because these components are connected to the faster data bus, either directly or via otherwise existing control units. This results in the elimination of the gateway functionality, and thus of separate gateways.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.